Foams that effectively reduce gas permeability were formed over a wide range of experimental conditions. The ability of selected foaming agents to form foam was evaluated in bulk foam measurements, screening core tests, and in reservoir condition core tests. Results reported show that oil usually adversely affected foam performance with higher molecular weight alkanes showing less of an adverse effect for the foaming agents tested. Foam can be effectively generated in an oil-wet porous medium but was shown to be much less effective than in a water-wet medium for the foaming agents studied. High pressure gradients of up to 4524 kPa/m (200 psi/ft) resulted in effective foam generation with an effective foam continuing to 8500 pore volumes of injected nitrogen. The enriched gas mixture used in this study was shown to adversely affect foam even though the foaming agent was selected through screening testing. This showed the importance of including reservoir condition testing prior to the final selection of a foaming agent for a given reservoir application. Effective foaming agents were identified for use in pilot tests in a typical West Texas CO2 flood and in a typical Canadian hydrocarbon miscible flood.

Seabed data acquisition methods offer numerous advantages over towed streamer data. These advantages can lead to improved static and dynamic reservoir characterization. By recording complete vector field data at the sea floor with full azimuth acquisition improved shallow resolution, signal-to-noise ratio, spectral content, deep imaging and 3D illumination can be achieved. Also in the presence of obstacles such as production facilities a regular coverage can be assured.Autonomous node technology has been developed to a fully commercial system. It has demonstrated improved imaging of complex reservoir with both pressure (PP) and converted shear (PS) with stable and consistent measurements achieved by very well planted nodes into the sea floor and full azimuth acquisition with densely sampled shots.It has been experienced that the background response from well planted nodes can be repeated in a 4C-4D scenario when the coupling conditions are the same. The vector fidelity in the node system will secure this behavior. In addition, the accurate positioning and re-positioning of the nodes under realistic water depth ranges gives positioning accuracy close to permanently buried cable systems. An experiment performed on the Volve field in the North Sea with pairs of nodes planted side by side clearly confirmed the high degree of stability in the coupling and the repeatability of the measurements from all components. At 100 m water depth all the planted nodes were within a short radius around the pre-plot position.A cost sensitivity study of different 4C-4D node scenarios depending of field size, water depths and node spacing indicates that, for larger field sizes (300-600km2 receiver coverage), the alternative use of nodes could be significantly more cost effective than permanently buried cable systems. Moreover, there are advantages linked to the acquisition geometry, operation, zero equipment life time risk and low initial investment.

In some micellar/~olymer flooding pilots, severe problems associated with polymer stability and/or polymer injectivity have been experienced. These problems have contributed to less than optimal pilot performances. As a result, process strategies which do not employ polymer have been actively considered.The sensitivity of the process to slug size, chemical concentration, capillary desaturation characteri sties, injection rate, microemulsion viscos.ity, and other design strategies wa~ determined.References and illustrations at end of paper. 785The results suggest that the current laboratory system is unacceptable for field testing because the system fails to produce sufficiently low interfacial tensions to significantly desaturate waterflood residual oil in the lower phase environment. The study does, however, point out useful goals, guidel~nes, and evaluation strategies by which the econom~c potential of future process designs can be assessed.

Summary Development of a sulfonate for use in a proposed 3-acre (12 129-m ) pilot test and a potential 200-acre (809 200-m ) commercial demonstration in the Salt Creek field Second Wall Creek reservoir (WC2) is summarized. Work emphasized development of a sulfonate manufactured from Salt Creek crude oil (CROS) or a feed stream from Amoco's Casper, WY, refinery. Advantages of the CROS product are in its expected long-term cost advantage, consistent feed stream quality, availability of feed stream, and reduced transportation cost when manufactured at or near a field location. This paper addresses the optimization and laboratory selection that went into defining the final product for more extensive fluid development studies. Experimental products were evaluated primarily on the criteria of micellar fluid stability and the oil displacement performance of single-phase micellar fluids. Core test studies evaluated the effects of manufacturing conditions and micellar formulation variables on oil displacement. Topping (light ends removal) of the WC2 crude before sulfonation was the most significant variable affecting the salinity tolerance of the products as well as the oil displacement performance. A 35% topping level was found to be optimum. Topping beyond this level further reduced salinity tolerance and reduced the oil displacement performance. Average equivalent weights and equivalent weight distributions were determined for selected products. Typically, oil-soluble alcohol cosurfactants, such as n-hexyl alcohol or Alfonic 610–50R (TM), improved oil displacements of CROS products. Salinities of in-place brines had little effect on the oil displacement performance over the range from about 8,700 to about 119,000 ppm TDS in core tests. Introduction The object of this work was to determine the feasibility of developing a crude oil sulfonate from a Salt Creek area stream that would be competitive in performance with a reference vacuum gas oil (VGO) sulfonate. This objective has been attained. The salinity tolerance range and oil displacing ability of CROS formulations indicate performance comparable with the VGO. Coupled with the other advantages of a CROS, it appears that a viable sulfonate candidate exists. The Salt Creek field is located in central Wyoming about 60 miles (96 km) north of Casper. In Aug. 1917, the WC2 producing zone of the Salt Creek field was discovered. The Light Oil Unit, which encompasses a major portion of the WC2 zone. has been the most productive portion of the field, producing more than 300 million bbl (47 × 10 m ) of oil since discovery. Waterflooding began in the WC2 reservoir in 1962. It is anticipated that waterflooding will extend the economic life of the WC2 reservoir until the mid-1990's. The WC2 formation is a muddy sandstone with a net pay of approximately 75 ft (22.86 m). Porosities range from 15 to 20% and absolute brine permeabilities are 10 to 100 md. Original water in place was low in satinity (13,367 ppm TDS), with less than 50 ppm hardness. Water from the Madison formation has been injected throughout the waterflood. Although low in salinity (about 2,500 ppm TDS), this water has a total hardness of about 350 ppm. The net effect has been to harden the clays in the waterflooded portions of the reservoir. This resulting satinity/hardness condition has been studied by Griffith. Because of this condition. ion exchange conditioning of the 3-acre (12 129-m ) pilot is being considered. Removal of calcium by ion exchange would be accomplished, before micellar injection, by injecting a bank of high-salinity water followed by fresh water. Crude produced from WC2 is somewhat waxy, and there is no measurable gas production at this time. JPT P. 2283^

No abstract